JPH0790294B2 - Shade mask forming method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shadow mask, and more particularly to a method for forming a shadow mask for a color picture tube.

2. Description of the Related Art There is a strong demand for thin flat tubes for cathode ray tubes used in recent televisions. In response to this request, the shadow mask used in the cathode ray tube has also become flattened. When the shadow mask is flattened, local deformation is likely to occur due to thermal deformation during image reception. To solve this problem, low expansion materials containing Ni have come to be used for shadow masks. This material has a high yield point and is poor in molding, so that it has a drawback in that the molding accuracy of the opening portion of the shadow mask and the molding of the peripheral portion cannot be satisfied. An example of the conventional molding method is shown in FIG.

FIG. 4 is a sectional view of the shadow mask during each step of the shadow mask molding process.

1a is a blank of a shadow mask, 2 is a punch as a tool for forming the blank 1a, 3 is an outer tool for forming the blank 1a with a die, and 4 is a wrinkle holder for pressing the blank and is attached to the outer periphery of the punch 2.

Reference numeral 5 denotes a pad attached so as to face the punch 2, and 6 denotes a pressure source for applying pressure to the wrinkle retainer 4, which is composed of a spring or a fluid cylinder. Reference numeral 7 is a fluid cylinder that applies pressure to the pad.

The operation of this conventional example is as follows. As shown in FIG. 4a, the blank 1a is placed on the die, and then the blank 1a is pressed by the crease clamp as shown in FIG. Then, as shown in FIG. 4c, the blank 1a is completed by sandwiching it with the punch 2 and the pad 5, and stops at the bottom dead center. Next, as shown in FIG. 4d, when the punch 2 and the wrinkle presser 4 are raised and the wrinkle presser 4 is raised to a height higher than the shadow mask, the shadow mask 1a is lifted from the die 3 by the pad 3 to complete one cycle. To do.

Problems to be Solved by the Invention As shown in FIG. 4d, the low-expansion material shadow mask has a problem in that the outer peripheral edge portion is curled and at the same time, the accuracy of forming the opening portion is poor.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention is in the process of processing the outer peripheral edge portion in order to improve the molding accuracy of the curl shape and the opening portion of the outer peripheral edge portion of the shadow mask of low expansion material. It is characterized in that the hole is stretched along the tool (punch) by applying a pulling force at the same time, and at the same time, the outer edge of the outer edge is stretched by applying a tensile force equal to or higher than the yield point, and then the outer edge is edged. To do.

Effect The present invention can form the shadow mask by pulling the aperture by changing the pressing timing of the wrinkle retainer and pressing or removing the outer peripheral portion of the shadow mask. Further, during the edging of the outer periphery of the shadow mask, the edge can be pressed again by the wrinkle presser to reduce the deformation of the tensile curl shape. By forming a gap between the wrinkle retainer and the shadow mask, the outer periphery of the shadow mask can be formed in a box-bent state, and curl deformation of the shadow mask can be reduced.

Example Hereinafter, one example of the present invention will be described with reference to the accompanying drawings.

FIG. 3A is a perspective view of a shadow mask molded product, FIGS. 1A to 1F are sectional views showing respective steps of the first half of one embodiment of the present invention, and FIGS. It is sectional drawing which shows a process. Here, 1b is a blank, and 8 is a punch for molding the blank 1b. 9 is a die for molding the outer periphery of the blank 1b. 10 is a wrinkle retainer that is attached to the outer periphery of the punch 8 to retain the blank 1b, 11 is a pad facing the punch 8, 12 is a spring or fluid cylinder that retains the wrinkle retainer 10, and 13 is a fluid cylinder that is pushing up the pad 11. is there.

In the drawing of the present invention, the punch is attached to the upper die and the die is attached to the lower die, but the processing timing is the same even in the opposite direction.

Next, the operation of the tool configured as described above will be described with reference to FIGS. 1 and 2.

Figure 1a shows a blank on the die 9 with the mold open.
1b and then blank 1b on die 9 as shown in FIG. 1b.
1 with a wrinkle retainer 10 and then punching with a punch 8 as shown in FIG. 1c to a range where the holes in the apertures of the shadow mask are not deformed (about 0 to 1.0 mm). Raise the wrinkle retainer 70 by 70 to 80% of the height of the outer peripheral edge of the shadow mask as shown in FIG. 1 and then squeeze the height H of 70 to 80% of the shadow mask as shown in FIG. Re-press the outer edge of the shadow mask with the creasing presser 10.

Next, the punch 8 is lowered while being held by the wrinkle retainer 10 and the height α corresponding to 2 to 5% of the outer peripheral height of the shadow mask is raised.
Drawing process. As a result, tension is applied to the entire formed portion of the opening portion, and at the same time, the edge portion H of the outer peripheral portion of the shadow mask is stretched and plastically deformed to be straight, as shown in FIG. 2a. Next, the wrinkle retainer 10 is formed again as shown in FIG. 2b with a gap larger than the remaining edge of the shadow mask. Next, the punch 8 is used to draw the shadow mask into the die 9 and the outer peripheral edge of the shadow mask is formed to stop at the bottom dead center as shown in FIG. 2c.

Next, the wrinkle presser 10 and the punch 8 are raised to raise the pad 11 upward when the height of the outer peripheral edge of the shadow mask is increased by more than the height of the outer peripheral edge of the shadow mask, as shown in FIG.

As described above, according to the present invention, by opening and closing the crease retainer during the formation of the shadow mask of the low expansion material, a tensile force is applied to the shadow mask to improve the forming accuracy of the shadow mask aperture and the outer peripheral edge. Curling deformation of the upright portion can be reduced.

[Brief description of drawings]

1a to 1f and 2a to 2d are views showing a processing process of an embodiment adopting the molding method of the present invention, and FIG. 3 is a perspective view of a shadow mask molded by the method of the present invention. FIGS. 6A to 6D are process diagrams of a cross-sectional view of a conventional molding die. 1a …… Blank material, 8 …… Punch, 9 …… Die, 10 ……
Wrinkle retainer, 11 ... Pad, 12 ... Spring or fluid cylinder, 13 ... Fluid cylinder.

Claims (1)

[Claims] 1. A blank of a shadow mask is pressed by a die with a wrinkle retainer, and the blank is sandwiched by a punch and a pad to form a desired shape, and an outer peripheral shape of the mask is drawn by the punch and the die. In the molding method, first draw a drawing depth of 1 mm or less, and between the wrinkle retainer and the die, the edge drawing height of the shadow mask is 70 to 80.
%, And then press the peripheral portion of the mask again with the wrinkle retainer and the die to hold the aperture portion of the mask with the punch and the pad and squeeze the aperture portion / peripheral portion again. Therefore, drawing at a yield point or higher is applied to perform drawing work at a height of 2 to 5% of the edge height of the mask, and a gap between the wrinkle holder and the die is such that the peripheral portion of the mask cannot be pressed. A method of forming a shadow mask, characterized in that the shadow mask is formed while being sandwiched between the punch and the pad.